Destroyer Whooper

Parts List:
         R1 = 6K8                     C1 = 470uF,25V electrolytic
R2,R4,R6,R7 = 1K                      C2 = 0.33uF, ceramic    
         R3 = 5K6                     C3 = 0.1uF (10nF), ceramic
         R5 = 10K                     C4 = 250uF/25V, electrolytic
         Q1 = 2N4401               U1,U2 = 555 Timer/Oscillator
         Q2 = 2N5400                  D1 = 1N914
                                   SPKR1 = Loudspeaker, 8 ohm       
	 
A complete KIT plus Printed Circuit Board will be available soon.

Destroyer Whooper Destroyer Whooper:
If you've ever watched any TV at all and seen those old WWII navy movies, you've heard that distinctive "whoop-whoop-whoop" as a destroyer sliced through the waves, guns blazing, and everybody yelling "battle stations!"

Well, I don't have a destroyer. What I've got is an old row boat with an outboard "put-putter" on the stern. But when I'm put-putting through the harbor on my way to my favorite fishing spot, I sure attract a lot of attention. You see, I built this "whooper", and it makes heads turn. If you really want to attract attention, feed the output to an amplifier first.

Integrated circuit U1 is connected as a low-frequency asymmetrical oscillator. Its output is inverted by Q1 and fed to the reset terminal of U2 at pin 4. Integrated circuit U2 is configured as an audio oscillator and is enabled when the output of U1 is low. With the voltage at pin 5 of U2 constant, the circuit would just "bleep".

The voltage across capacitor C1 is fed to the base of Q2, turning it on and grounding pin 5 of U2. When the frequency of the reset signal on pin 4 falls, the output frequency of U2 rises. The output then becomes a whoop, starting low in frequency and ending high.
Resistor R1 sets the repetition rate and R2 determines the time duration of the whoop. Resistors R3 and R4 set the center-operated frequency.

Copyright:
This article is © and was submitted by Murray Stein, Miami Florida, to Byron G. Wels' 'Think Tank' section in Popular Electronics Magazine, July 1989 and published by Gernsback Publishing (no longer in business).